<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<script>
/* 			var x =10;
			console.log(x);
			{
				var x =100;
				console.log(x);
			}
			console.log(x); */
			//es6的新标准，变量
			let x =10;
			console.log(x);
			{
				let x =100;
				console.log(x);
			}
			//代码段中let定义变量作用域，代码段结束，里面的x也结束
			 console.log(x);
			//js只有变量没有常量定义，es6中定义常量
			const var sysname ="学生管理系统";
			//sysname ="mis";
			console.log(sysname);
			const var PI =3.14;
			console.log(PI);
				//PI=3.1415926;
		</script>
	</head>
	<body>
	</body>
</html>
